1. Field of the Invention
The present invention relates to a vehicle navigation system, and more particularly, to a method for guiding path of a complex intersection.
2. Description of the Related Art
A vehicle navigation system is an equipment that calculates paths in order to guide a vehicle to a driver's intended destination and provides a drive instruction to the driver in consideration of current vehicle position and drive direction such that the vehicle is driven along the calculated path.
A global positioning system (GPS) recently employed in a vehicle navigation system is a satellite navigation system that is originally developed by the Department of Defense. The satellite navigation system receives a radio wave signal generated from three or four satellites in which an atomic frequency is loaded, calculates a distance to the satellite using a propagation time of the received radio wave signal, and measures a speed using three (or two) dimensional determination and a Doppler effect of radio wave.
The navigation system is originally developed for a military purpose. Afterwards, considering a utility value of private transport means, the navigation system transmits radio wave signals having a distance error from satellites so that civilians can use it.
Accordingly, an information used for vehicle movement, such as distance and time to destination, can be obtained using the GPS satellite signal.
According to the vehicle navigation system using the GPS, when a satellite radio wave signal is inputted through a GPS directional antenna mounted outside the vehicle, an information on latitude and longitude is outputted by a GPS tuner.
The information is processed in a central processing unit together with wheel rotation signal and data inputted through various sensors of the vehicle, and an arrival expectation time is calculated, and the result value is displayed on a display device.
Typical vehicle navigation systems are classified into a path searching scheme and a path guiding scheme. The path searching scheme can be implemented with two methods. One method is to calculate path within a vehicle by using only geographic information and position information which are loaded in the vehicle. The other method is to receive an information calculated by a remote server through a transmission of a vehicle position information.
As the path guiding scheme, there are a turn by turn method of providing a drive information for path following and a method of providing a surrounding geographic information together with a path instruction in a drive state.
Here, according to the path searching scheme, a method of receiving the information calculated by the remote server through the transmission of the vehicle position information can include various information, such as real time traffic information, in a path selection. However, there is a limit that all path guidable information is dependent on a reception from a server. Additionally, in case the method of receiving the information calculated by the server through the transmission of the vehicle position information is applied, the method of instructing the drive information for path following can be used together in the path guiding scheme because the vehicle does not have the path surrounding geographic information.
In general, a conventional vehicle navigation system uses a method of displaying a surrounding map and providing a surrounding geographic information together with a path indication in order for a map searching, in which a surrounding information of a navigation numeric map is directly displayed to the user to thereby provide an intersection information.
In case such an intersection information is guided to the user, the method of receiving the information calculated by the server and the method of instructing the drive information for path following have a limit that an intersection guidance must be performed using a guidance indication because the methods do not display the surrounding map.
At this time, although a path guidance time point and a guiding scheme maintains the conventional method, a judgment standard must be precisely defined in order to display the corresponding intersection on a screen to provide the drive instruction, not the surrounding map information.
FIG. 1 is a view exemplarily showing a representation of an intersection. As shown in FIG. 1, an intersection that a driver generally judges as one intersection is represented with a road network of a navigation numeric map. The intersections are classified into two types. One is a single intersection configured with one node, and the other is a complex intersection configured with a plurality of nodes although the driver may judge it as one intersection. Here, the complex intersection can be represented differently according to passage network inside the intersection, geographic factors, types of an adjacent supplementary road network incorporated into an actual intersection, and so on.
Since the representation of the single intersection assumes the display of the surrounding map, a judgment standard for conditions of the complex intersection is not reflected. Therefore, only an icon of a rotation instruction is displayed auxiliarily.
However, in case of the turn by turn scheme, it is difficult to transmit information appropriate to the drive guidance by using a rotation icon since there is no method except for a method for displaying conditions of adjacent roads through an intersection pattern.
FIG. 2 is a schematic view of a screen that guides paths of a complex intersection according to a related art. As shown in FIG. 2, the complex intersection is configured to be applicable to a map format standardized for a configuration of a complex intersection information. However, in case of an application of an actual guidance, a generation standard of an actual complex intersection node is unsuitable for a representation of one intersection since a broad area, not a rotary intersection which is an actual guidance target, is grouped.
Additionally, the complex intersection has a single position information and a cost by representing a supernode with one representative node, and includes an internal road network as an attribute. In other words, the supernode is also used for a path searching and guidance as one node. On the contrary, a vehicle navigation system of communication-based turn-by-turn scheme stores the searching path received from a server in a type of node/link sequence, instead of the navigation numeric map recorded on CD/DVD containing a large capacity geographic information, and uses it for the path guidance. Accordingly, there is a difficulty in extracting the searching path, which is configured with a general node and link, and the guidance data by dividing the supernode in order to apply only the representation of the path guidance.